Question

What is meant by a body at rest

Answer 1

A body at rest may be defined as follows:

A body is said to be at rest, if it does not change its position with respect to a fixed point in its surroundings.

For example, a book lying on a table, if not disturbed by anybody, does not change its position with respect to the table, the walls of the room, etc. So, a book lying on a table is at rest.